Numerical study on the settlement of two parallel spherical particles in upward flow

The settling of particles in fluid flows is a common occurrence in various industrial processes. Investigating the interactions between particles and fluid during settling holds significant importance. This article presents a numerical study of the settling process involving two parallel particles in upward flow, employing the immersed boundary method (IBM). The simulation data were validated using experimental results for single spherical particle settlement, two parallel spherical particles settlement, and the settlement of two series of spherical particles. A comparative analysis was conducted between particle settling in upward flow and static fluid. The study explores the impact of different upward velocities and initial particle spacing on particle settling. Results indicate that the wake generated by the two parallel particles in upward flow forms a distinct boundary with the surrounding fluid. As the upward velocity increases, this boundary becomes increasingly observable. In comparison to settling in static flow, the repulsive effect between two parallel particles in upward flow is stronger, and the settling velocity of particles is smaller. Furthermore, the study reveals that the repulsion between two particles diminishes rapidly with an increase in the initial spacing, but the final settling velocity of particles remains nearly constant.